The use of indicia of various kinds to generally indicate the amount of tape or film on a spool is readily recognized. Philips-type audio cassettes as well as VHS and Beta type video cassettes have for years been supplied with ribs molded into the cassette enclosures which are intended to allow the user to estimate the relative amount of tape on each spool, and from that, assuming the user to be aware of the tape speed, to calculate the available running time. Such indicators are notorious for the confusion resulting when one attempts to use them, with the result that they are virtually totally disregarded. One attempt to improve the accuracy of such indicators is presented in U.S. Pat. No. 2,937,818 (Zorn), wherein matching bars are molded on both the take-up spool and on the window of the tape container, thus allowing the user to align the matching bars to avoid parallax errors. That patent suggests providing two measured divisions, one being graduated in units of length and the other in time. U.S. Pat. No. 3,718,290 (Wright) is exemplary of prior suggestions for providing accurate indications of prerecorded selections on a prerecorded tape, and depicts a transparent window adapted to be inserted in a tape container and having a series of opaque dots corresponding to the beginning of prerecorded tape segments.